ABSTRACT
<p><b>OBJECTIVE</b>To map the disease locus for a congenital cataract family, and detect the disease-causing gene.</p><p><b>METHODS</b>An autosomal dominant congenital cataract family was genotyped by genome wide scan using 382 autosomal microsatellite markers from ABI-MD10. Two-point linkage analysis was carried out by the MLINK program.</p><p><b>RESULTS</b>The disease locus of this family was mapped at 12p11.2-q15. Sequence analysis of a candidate gene-major intrinsic protein (MIP) revealed a novel missense mutation G-->A at the nucleotide 702 in exon 4, which resulted in a substitution of arginine to lysine at codon 233 (p.R233K).</p><p><b>CONCLUSION</b>The mutation G-->A at nt702 in MIP gene was associated with the binocular polymorphic congenital cataract in the family. This transition occurring at the C-terminus of MIP might decrease the stability of the C-end of the protein and impact the function of the protein.</p>